Radiology Coding Alert

Look for injection or inhalation to determine perfusion or ventilation scans.

When your radiologist performs a ventilation/perfusion scan (or VQ scan) to help rule out a suspected pulmonary embolism, you might encounter terms such as "MAA" and "DTPA" in the clinical notes. The challenge is that you won’t be able to locate these terms in the CPT® code descriptors. This can be confusing, and can cause coding inconsistency — putting your practice at compliance or financial risk.

In order to code with consistency, you will need to confirm if your physician provided a perfusion or ventilation service. Check out these refresher tips to help you with your ‘whys and hows.’

Proceed With an Injection Using 78580

If the radiologist wants to learn how well a patient is getting oxygen into the blood, he’d generally measure two things:

1 How well the blood is getting down into the capillaries surrounding the alveoli (air sacs) in the lungs (perfusion).

2 How well the oxygen is getting down into those same alveoli (ventilation).

A pair of nuclear scan tests — pulmonary ventilation/perfusion scan — will accomplish this purpose.

Definition: A VQ scan uses inhaled and injected radioactive material called radioisotopes to measure breathing (ventilation) and circulation (perfusion). The physician may perform these tests separately or together.

During a perfusion scan, a provider injects radioactive albumin into the patient’s vein. This material travels through the vascular system, allowing for a scan of the patient’s lungs as blood flows through them to detect the location of the radioactive particles. To describe a service that is specific to perfusion, you would use 78580 (Pulmonary perfusion imaging [e.g., particulate]).

"In perfusion imaging, a radiopharmaceutical agent is injected (TC-99m MAA) to evaluate pulmonary arterial blood flow in the lungs," says Stacie L. Buck, RHIA, CCS-P, RCC, CIC, President & Senior Consultant, RadRx, Stuart, Florida. The physician would likely refer to macroaggregated albumin (the radioactive particles injected into the patient’s vein) in the report of a perfusion scan service. You may see it documented as "Tc-99m- MAA, MAA" or "Technetium MAA". The term "macrospheres" can also narrow your choice to a perfusion study.

Tip: Look for the injection of the radioisotope to differentiate between perfusion and ventilation. This is unique to perfusion.

Note: The code descriptor of 78580 mentions the term ‘particulate.’ This refers to the use of radioactive particles in the scan. "The term particulate implies that during the exam, a scanner is used to identify the location of the radioactive particles," explains Buck.

Relate Ventilation Study to Aerosol and Gaseous Radioactivity

When the documentation says the patient inhaled the radioactive substance for a lung scan -- instead of getting it injected -- you would report 78579 (Pulmonary ventilation imaging [e.g., aerosol or gas]). "A ventilation scan will use either Xe-133 (gas) or Tc-99m DTPA (aerosol)," says Buck. You report a ventilation scan when your radiologist documents that the patient inhaled a radioactive gas (generally xenon) or the patient inhaled oxygen that had been aerosolized with particles of a radioactive substance.

What happens: During a ventilation study, the provider places a mask over the patient’s mouth and nose so he breathes in the radioactive material while images are taken to measure air flow in and out of the lungs. When determining if the physician performed a ventilation study, you may see clear documentation, for instance the word "ventilation." "The ventilation scan assesses the distribution of the radioactive gas in the lungs," says Buck.

Documentation tip: The key term to look for indicating aerosol is "DTPA," the radioactive aerosol the provider has the patient inhale, says Becki Garaud, CPC, CPCE/M, RCC, compliance education and coding trainer for the University of Washington Physicians and Children’s University Medical Group Compliance Program. Other terms you might see indicating aerosol include "Technetium DTPA", "particulate," and "mist."

Meanwhile, you may identify gaseous ventilation studies from references to the gas used, typically xenon gas (such as Xenon-133 or Xe 133), says Garaud. Another possibility is krypton gas (Krypton-81 or Kr 81), although you may not see this much in practice.

Don’t Forget the Combo 78582

Perfusion and lung ventilation scans almost always go together. Your radiologist would often perform these procedures jointly to detect a characteristic pattern of perfusion deficits. Together, these procedures provide an accurate noninvasive screening test both for the detection of emboli and for documentation of resolution during and after therapy. In this case, you would be safe coding 78582 (Pulmonary ventilation (e.g., aerosol or gas) and perfusion imaging), which combines codes 78580 and 78579.

CPT® 78582 describes a combined procedure to determine both pulmonary perfusion and ventilation. You would report 78582 when your radiologist obtains the images once after inhalation of a radioactive aerosol to determine pulmonary ventilation and again after injection of a radioactive particulate to determine lung perfusion.

Important: You should report 78582 regardless of the number of projections that were performed as part of the pulmonary perfusion procedure. This helps eliminate the misuse of modifier 52 (Reduced services) to indicate reduced services. For instance, if you do only one part of the 78582 procedure, you can just report the perfusion code 78580 or the ventilation code (78579) -- no need for you to append modifier 52.

Report Discrete Codes for Differential Scans

Your radiologist may do a differential perfusion in patients with unequal distribution of blood flow in the lung. You report 78597 (Quantitative differential pulmonary perfusion, including imaging when performed) for differential pulmonary perfusion and 78598 (Quantitative differential pulmonary perfusion and ventilation (e.g., aerosol or gas), including imaging when performed) for differential pulmonary perfusion and ventilation.

Note that codes 78597 and 78598 are inclusive of the imaging, when done. The imaging can be a magnetic resonance imaging (MRI) or other radiological imaging that your radiologist obtains during the scan. You do not report any additional codes for the imaging.

For any other diagnostic nuclear respiratory procedure, you can report code 78599 (Unlisted respiratory procedure, diagnostic nuclear medicine).